To meet United Nations targets for limiting global warming by 2100, governments may have to extract large quantities of greenhouse gases from the air and invest trillions in clean energy, according to a U.N. draft report seen Wednesday by Reuters.

Emissions will have to fall by as much as 70 percent between 2010 and 2050 to slow climate change, the 29-page report summary says. To meet the goal of keeping warming to under 3.6 degrees Fahrenheit, the world will have to not only start employing “carbon dioxide removal” technologies, but radically shift its energy investments, putting $147 billion toward low carbon energy sources, like wind, solar, and nuclear power, between 2010 and 2029, and reducing fossil fuel investment by $30 billion every year.

The world can also help meet its energy needs while reducing greenhouse gas emissions by building more energy-efficient cities.

“Most of the world’s urban areas have yet to be constructed,” the report says.